This article defines mobile learning. Its functions and models are analyzed. The functions are divided into didactic, technical and communicative. Main differences between m-learning and e-learning are examined. Three pedagogical models are reviewed, teacher and student centered. The m-learning model is introduced based on our analysis. It consists of four components: educational, communicative, technical, and organizational. Each of these components has its functional purpose. They are either resourceful or systematic. The conclusion is given that despite its informal characteristics m-learning is rather systematic. The model, presented in the article, is generalized and can be used to classify different mobile applications and models of using mobile devices in teaching a foreign language.